This invention relates to a trimming device for a marine propulsion apparatus and more particularly to an improved control arrangement for such a trimming device in which the trimming condition of the marine propulsion unit is set automatically in response to a predetermined speed of the propulsion apparatus.
As is well known, a wide variety of marine outboard drives are supported for movement relative to the transom of an associated watercraft between a plurality of trim adjusted positions. The outboard drive may comprise an outboard motor or the outboard drive portion of an inboard/outboard arrangement. In either event, the optimum trim position of the outboard drive will be determined by a wide variety of factors and the trim adjustment permits operating at the aptimum trim angle under all of these characteristics. Frequently, a power device is provided for achieving the trim adjustment and some form of control operates the power device so as to achieve the trim adjustment. A wide variety of manual and automatic controls have been provided for this purpose.
Although automatic controls offer the advantage of reducing the likelihood of operator error in setting the trim position or in failing to change the trim position when dictated by different running conditions, the automatic controls are not fully satisfactory. The reason for this is that many of the conditions involved in the running of a watercraft vary instantaneously and unless some form of damping mechanism is employed, the automatic trim adjustment will continue to hunt for the optimum position. On the other hand, fully manual controls are not completely satisfactory because the operator may at times forget to readjust the trim position of the outboard drive even though the running conditions dictate such a change in trim position.
It is, therefore, a principle object of this invention to provide an improved trim device for a marine propulsion apparatus.
It is a further object of this invention to provide a trim apparatus for a marine outboard drive in which the main control is manual but automatic control is provided under certain running conditions.
It is a further object of this invention to provide an improved semiautomatic trim control for a marine outboard drive wherein the outboard drive is automatically trim adjusted in response to a speed condition of the propulsion device.